Multi-domain DKIM signature with OpenSMTPd

[Matthieu]

Hi everybody
I'm looking to use OpenDKIM with OpenSMTPd. Has anyone ever done it 
before ?
My first intention is to sign mails from different domains on a single 
mail server. So the

OpenDKIM works with a socket and I don't know how and if it works with 
the smptd filter.
I've seen the «opensmptd-filter-dkimsign» packet, but we can only 
specify one domaine.

Otherwise I'd be looking at the side of dkimproxy if it can do the job 
or not.

Thx for any help.